Bone marrow has generally been harvested using a bone marrow puncture needle to manually puncture the ilium. This kind of bone marrow puncture needle is constructed in such a manner as to insert and fit an inner needle into a tubular mantle while allowing the tip of the inner needle to project from the mantle. The bone marrow puncture needle, which is equipped with a handle in the mantle, percutaneously punctures the ilium, and once the tip of the needle reaches bone marrow, the inner needle alone is drawn out and the mantle remains in contact with the bone marrow for subsequent use.
As a method for harvesting bone marrow using this bone marrow puncture needle, typically, an aspiration method is employed. The aspiration method is such that the mantle of the bone marrow puncture needle is connected to a syringe to collect bone marrow by virtue of the aspiration force. In this method, however, since the quantity of bone marrow harvested from one site of a bone is as small as several ml, collecting a sufficient quantity of bone marrow requires a number of sites to be punctured. Further, a large amount of peripheral blood is allowed to mix into the harvested bone marrow. Consequently, the method, when used in allogeneic bone marrow transplantation, carries a high risk of causing GVHD (Graft versus Host Disease), which necessitates immunosuppression.
Under these circumstances, a bone marrow perfusion method has been developed as a method for overcoming the above problems. In the bone marrow perfusion method, two bone marrow harvesting needles are placed in contact with bone marrow so as to slowly perfuse bone marrow with a perfusion medium such as sterilized physiological saline. One of the needles is connected to a bone marrow harvesting set, and a bone marrow harvesting bag of the set is connected to an injection syringe or a tube of a parenteral fluid pump to aspirate bone marrow. Using a syringe that is filled with a perfusion medium and is connected to the other needle, the perfusion medium is injected slowly into the bone marrow in such a manner as to wash away the bone marrow, and thereby a required quantity of the bone marrow is harvested into the harvesting set in a short time. The bone marrow harvested in this way can be used not only for bone marrow transplantation but also for regenerative medicine.
However, the bone marrow puncture needle that is conventionally employed, which is constructed to be inserted into a bone manually by holding a handle, is not suitable for application to the bone marrow perfusion method from the viewpoint of the puncture rate and other factors.
Thus, a method has been desired that drills and punctures a bone in a short time using a bone marrow harvesting needle equipped with an electric drill that is capable of providing powerful rotational power. For this reason, a bone marrow harvesting needle has been proposed that includes an inner needle with a drilling edge; and a mantle with an angled edge formed at its tip, the mantle being allowed to rotate at a reduced speed with respect to the rotation of the inner needle through a speed reduction mechanism (WO 03/015637). This bone marrow harvesting needle makes it possible to reach the cavity accommodating the bone marrow in a significantly shorter time, and is also excellent in that bone scraps are discharged to the mantle, not into the body, because the bone scraps produced by the angled edge at the tip of the mantle are discharged upward in the mantle along a groove of the drill part of the inner needle. However, the viscosity of collagen, etc., contained in bone tissue resists the discharge of the bone scraps, thus limiting the reduction in the drilling time.